Basic Troubleshooting

After you get your modular going, at some point you're gonna be patching stuff and suddenly it wont work - i guarantee, it's gonna happen. DON'T PANIC!

before you get that horrible sinking feeling in your stomach where your head is going 'halp! i blew up my best friend', read this.

although the only general rule with modulars is 'dont follow rules', i.e. be creative in an intelligent way when everything is working, when there's a problem the rule is always 'have patience and use logic'.

This post is making some general assumptions again:


 * i. when you installed your modules into the case you followed info from manufacturers power etc, hence plugged in modules correctly without lowing anything up.


 * ii. you have got the basic minimum of modules required to make a sound - i.e. bare minimum is something that oscillates at audio frequency, and most likely a set up like this East Coast, single VCO mono patch

to find the trouble, it helps greatly to follow this process - basically working through the signal path step by step:


 * a. plug just the VCO straight into your amp/mixer/phones. there should be a constant tone produced (check frequency and waveshape etc - you may have it outputting below audio frequency for example?)


 * b. now plug your control device, i.e. whatever you use to provide the 1v/oct signal to the VCO pitch cv in. you should still hear a constant tone, but the pitch should change when you press a key or a sequence runs. (if nothing happens to the tone, try using an alternate cv source like an LFO - this will help you find out if the control device is sending a signal)


 * c. insert the filter between the VCO output and the amp/mixer/phones. when you adjust the cutoff and resonance you should hear the continuous tone from the VCO change (depending on the filter settings you might get a piercing squeal with hi resonance or no sound if the filter is attenuating the frequency output by the VCO)


 * d. send a gate signal to your EG and the output of the EG to the filter cutoff. each time you send a gate signal the EG should shape the filter sound (a fully open LPF can't open more - nothing will happen when you send a positive envelope. also check any cv amount knobs - if they're at zero then the cv from the EG wont do anything.)


 * e. insert a VCA inbetween the filter and your amp/mixer/phones. move the envelope cv going to the filter to the VCA cv input. there should no longer be a continuous tone (if there is you probably have some gain/initial/offset /etc. knob turned up too far on the VCA). now when you send a gate signal the previously continuous tone from the VCO should, depending on your EG settings, become audible then stop again. (long attack will take time to become audible, long release will take time to die away).

if you have progressed this far, and your basic patch is all behaving then you can test any individual modules or parts of a patch in the same logical fashion - switch audio generating modules or cv generating modules with the VCO or EG etc. as appropriate and wiggle some knobs to see if they are behaving right - since you have checked everything else it should be easy to identify a problem such as one knob silencing the sound or one output/input distorting the sound etc.

this same technique applies to any patch, but be very aware, once you progress past this basic 'East Coast Patch', you will find that often one knob affects multiple modules in the patch, there can be dead spots where the phase of a particular wave cancels out another etc. not everything works at every setting.

WARNING!!! this technique is grand for testing things/tracking down errors/investigating new modules or patches whilst in a framework you know works or behaves very predictably, BUT, please - dont take this as a setup you must use to create every sound - there's so many other ways to patch your modules!

at the very least try patching your LFOs, other VCOs, EGs, Sequencers and even VCAs into whatever cv in you can think of - and when you've explored these avenues, try FM (audio frequency oscillators as cv sources), using envelopes to shape other cv sources rather than just supplying a cv directly etc. short of patching output to output or someother module specific not to do's that manufacturers warn about, do ANYTHING!!!